Demonstrable benefit can be realized by temporarily, repositionably, and nondestructively attaching power tools such as drills to workpieces such as the skins of aircraft under construction, which attachment may enhance tool operation—specifically by replacing hand operations with machine-controlled operations, to improve hole location, angle, diameter, and degree of uniformity. Attaching tools to the workpieces can be beneficial in many manufacturing arts, including, among others, manufacture of aircraft and other vehicles, and of static structures.
A typical arrangement uses a rail and a drive mechanism. The rail comprises a long strip of relatively wide and thin metal attached to many vacuum cups so that the rail can be drawn into close conformance to the shape of a workpiece, where the workpiece may be for example a relatively large piece of sheet metal or other sheet material such as carbon fiber-reinforced plastic. Such a rail sits above the workpiece and is sturdy enough to support a power-operated tool, such as a drill. The exact location of the tool on the rail and on the workpiece may be critical to the quality of the workpiece and may be measurable. In the prior art, a slideable mounting of a tool along the rail can use vee guides on the tool attachment mechanism (hereinafter toolhead), which vee toolhead guides may be for example female, and may be clamped to and free to slide along mating male vee guides that are integral with the rail. A representative complete prior art apparatus may use a pair of such rails independently vacuumed down to a surface, with one of the rails geared to a toolhead using a motorized and direct-measuring drive and the other allowing free sliding of the toolhead.
Moving a toolhead on a rail can be accomplished using positively coupled, that is, slip-free, drives, such as a motor driven pinion gear whose shaft may be parallel to a transverse axis of the rail. As the motor rotates in such prior-art devices, the pinion drives the toolhead along a rack. A transducer such as an encoder may be used to measure the position of the motor (and the toolhead) with respect to a reference point on the rail.
While successful in prior use, drive systems using the above-described rack technology have at least one significant drawback. It would be desirable that the rail remain flexible to permit both thin-axis bending and twisting, yet permit highly precise positioning of the toolhead.
Accordingly, it is desirable to provide a flexible track rail and toolhead containment system that provides robust and precisely measurable positioning of the toolhead while permitting the use of a simple rail that is relatively easy to fabricate.